Universite´ Pierre et Marie Curie, Paris, France and University of Edinburgh, United Kingdom

The gross composition of planets is controlled by the condensation sequence (Fig.1a) in the early solar system. Refractory materials such as silicates and iron condense at high temperatures, while the so-called planetary ices (any compound in the CH4-NH3-H2O system, either in the liquid or solid state) may condense only in the colder outer parts of the solar system. Jupiter and Saturn therefore reached sufficient masses to attract H and He gases blown away from the Sun. As a result, the bulk of planets consists of three main compositions: silicates and iron for the inner terrestrial planets, H and He for Jupiter and Saturn, and planetary ices for Uranus and Neptune. In order to get insights on the structure and dynamics of planets, a number of properties need to be measured, on the relevant materials for each planet and at the relevant P-T conditions (Fig.1b). Those properties are briefly summarized in Table 1. The type of properties to be measured can also be guided by the available observational data (e.g. accoustic velocities on terrestrial materials to be matched with seismic profiles).